Heat production control arrangement



Feb. 10, 1942. F. J. WEYHER I 2,272,492

HEAT PRODUCTION CONTROL ARRANGEMENT Filed Nov. 21, 1958 OUTDOOR TEMPERATURE I Patente Feb. 10, 1942 C'EION CONTROL duction control arrangement by means of which the rate heat is supplied to the interior of an enclosed structure is made approximately equal to the rate heat is lost from the structure to the outside at a certain desired inside temperature,

whereby the interior of the structure is auto- GEMENT Frederick J. Weyher,'Chicago, 111., assignor to Kenneth C. Brown, Evanston, Ill.

' Application November 21, 1938, Serial No. 241,545

My inventionrelates to an improved heat pro ous radiators (not shown) in the structure. The furnace I3 is equipped with an electrically operated stoker is which comprises a hopper 20,

adapted, to hold finely divided fuel such as coal,

and an electric motor 2 I.

My improved arrangement is provided with two thermo-responsive regulating members, a boiler member 22 which projects into and through a side of the boiler 16 and an outside member 23 be economically heated with little or no variation of inside temperature notwithstanding the changeable external weather conditions to which the building is subjected.

It is another object of my invention to provide a heat production control arrangement of this type in which the adjusting means may be calibrated readily to cover the variety of conditions likely to be met in practice.

It is also an object of my invention to provide an arrangement of this type in which the latitude of adjustment in a single embodiment-of the arrangement is such that it can be used with a varietyof difierent types of heating systems, for example, with both steam and hot water.

It is a further object of my invention to improve arrangements vof this type in sundry details hereinafter pointed out. The preferred means by which I have accomplished my several objects are illustrated in the drawing and are hereinafter specifically described. That which I believe to be newand desire to cover by Letters Patent is set forth in the claims.

In the drawing:

Fig. 1 is a vertical sectional view of a building structure having associated therewith an emarrangement is of the steam variety and which includes a furnace I3 in the basement N of the structure. The furnace comprises a fire-box IS; a boiler I6 partially filled with water, the upper surface of the water or the water line being indicated at 51; and an outlet main l8 by means sf which steam is fed from the boiler to the variimmediately adjacent to the fines.

which is positioned outside of and ad acent the structure It] on one of the side walls ll. Both of the thermo-responsive members are positioned such that they will be as closely as possible at the temperature of the immediate surroundings.

The boiler member 22 is-preferably a few inches below the water line I! in the boiler and is'not The outside member. 23 is preferably located such that it is not exposed to the sun and is not unduly exfposed to the wind. The regulating members 22 and 23 each comprise, in the illustrated embodiment of my arrangement, a resistance elementwhich has a comparatively high temperature coemcient of resistance; that is, the change of resistance-of each member is'comparatively great with a change of the surrounding temperature.

The boiler member 22 is connected by means of leads'24 into one arm of a'Wheatstone bridge structure 25 comprising resistance elements 26,

21, 28, 29 and 30. The outside member 23, is

connected by means of leads 3! into a similar Wheatstone bridge structure 32 comprising resistance elements 33, 34, 35, 36 and 31. As is shown, the resistance elements 21 and' 34 are adjustable; that is, their resistance values may be changed at will. A uni-directional electric potential is applied across one diagonal of each of the bridges, across bridge 25 between points 25a and 25b by means of leads 38 and 39 and across bridge 32 between points 32a and 32b by means of leads and 4 I. An adjustable resistor 42 in lead 4| is connected in series with the bridge 32, ,and a filter condenser 43 is connected between leads 39 and it, as shown. Leads 39 and M are commonly connected to a lead it which is center-tapped to a secondary winding 45 of a transformer t6. Leads 38 and 40 are commonly connected to a lead 81 which centertapped to another secondary winding 68 of the transformer 46. The terminals of the secondary winding 4.8 are connected by means of leads &9 with the plates 56 and 5!, of a double wave rec.- tifier tube 52. Leads 53 connect the cathode 54; of the tube 52 with the secondary winding 35,

the cathode being supplied with current thereby. The primary winding 55 of the transformer 66 is connected to a source of alternating current of a suitable voltage and frequency.

The bridge 25 across its diagonal between points 250 and 25d is connected in series with and between the control grid 56 and the cathode 51 of a gaseous discharge tube 58. The grid 56 is connected to point 250 by means of a lead 56 having therein a stabilizing resistor 60. The cathode 51 is connected to the point 25d by means of leads 6i, the secondary winding 62 of a transformer 63, and leads 64, 65 and 66. As shown, the lead 64 center-taps the secondary winding 62 which by means of leads 6! supplies energy to the. cathode 51 for heating it. Between the cathode 51 and the grid 56 is connected a condenser Bl by means of leads 68, as shown.

The bridge 32 across its diagonal between points 32c and 32d is connected in series with and b tween the control grid 69 and the cathode 61. The grid 69 is connected to the point 320 by means of a lead 10 having therein a stabilizing resistor II. The cathode 5! is connected to the point 3212 by means of leads 6i, the transformer winding 62, and leads 64, 65 and 12. Connected to the plate 13 of the tube 58 by means of a lead It is a relay 15. In series with the relay by means of lead 16 is connected a-secondary winding 11 of the transformer 63, the winding 11 being in turn connected to the center-tap 64 by means of a lead 18. The relay contactor a actuated by the armature (not shown) of the relay i5 is connected by means of lead 19 with the motor 2|. Between the lead 60 which is connected to the stationary contactor 15b of the relay and the lead 8| which is connected to the motor 2i is'applied a voltage having a value suitable for operation of the motor. The primary winding 82 of the transformer 63 is connected with a source of alternating current of a suitable frequency and voltage.

The adjustable shunting resistance 83 which is connected between leads l0 and I2 by means of leads 84 and 85 may be used instead of or in addition to the adjustable resistor 42 and for the same purposes which are hereinafter stated.

My improved arrangement maintains a. substantially constant inside temperature by causing the rate of heat supplied to the interior of 6 a structure to vary with the outside temperature and to be maintained approximately equal to the rate of heat loss of the structure at the desired inside temperature. In Fig. 2, for a certain steam-heated building, as an example, I have shown a graph illustrating how the boiler temperatures should be varied as the outside temperature varies inorder that the rate of heat supplied will be properly varied. My improved arrangement automatically causes the temperature of the supply to vary properly with the outside temperature.

The rectifier comprising the tube 52, the transformer 46, and the filter condenser 43 is of an ordinary and well-known type and supplies a substantially unilateral voltage across the diagonals of the bridges 25 and 32 between their points 25a and 25b and between 32a and 32b, respectively. In the embodiment of the control arrangement shown, the voltages of points 25b and 32b are positive with respect to points 25a and 32a, respectively.

Normally the bridges 25 and 32 are unbalanced such that there is a voltage across the diagonals of the bridges between points 250 and 25d and between 320 and 32d. Since points 250 and 320 are connected to grids 56 and 69, respectively,

and since the points 25d and 32d are connected to the cathode 51., the voltages across the diagonals of the bridges formed by these points are impressed between the grids 56 and 69, respectively, and the cathode 51.

The gaseous discharge tube 58 is so constructed that an arc will not be formed between the cathode 51 and the plate 16, and hence no plate current will flow, unless the eifective sum of the a bias voltages between the grids 56 and 69 and the cathode 51, both voltages being reduced to a common base, is sufficiently positive. Depending on the construction of the tube, one grid may exert more influence than the other; that is, a change of one volt in the positive direction on grid 56 may cause the plate current to flow while it may require a change of two volts in a positive direction on grid 69 to accomplish the same result. For this reason, in order to reduce the bias voltages to a common base and to determine their eifectlve sum, it is necessary to multiply each value by an appropriate constant before adding. In any event, if the voltage on one grid is constant, the voltage on the other grid must be more positive than a certain critical value in order that plate current may flow. In the illustrated form of my arrangement. a gaseous discharge tube having negative break-down characteristics is used; that is to say, a tube in which the grid biases are negative at break-down for most of the values of plate voltage which may be used.

The stabilizing resistors 60 and ii are used to protect the tube 58 by limiting the current to the correct values in the grid circuits. The condenser 61 is used to hold the voltage on the grid 66 steady in spite of the plate to grid capacitance and is particularly useful in protecting the tube against voltage surges.

' The temperature of the outdoor thermo-responsive member 23. determines its resistance, the magnitude of the unbalance of the bridge 32, and thus the voltage on the grid 69 with respect to the cathode 51. -The temperature of the boiler thermo-responsive member 22 determines, similarly, the voltage on the grid 56 with respect to the cathode. Assuming that the heat production. control arrangement has been adjusted to correspond to the curve shown in Fig. 2, the method of adjustment being hereafter described, and assuming that the outside temperature is constant, for example at a point 86 on the graph of Fig. 2, if the boiler water temperature is slightly higher than the corresponding point 81 on the curve, the resistance of the boiler member 22 is comparatively high and there is a comparatively large unbalance in the bridge 25. The voltage bias on the grid 56 is then more negative than the critical discharge value for that grid at that particular outside temperature and at the corresponding voltage on the grid 69, and no plate current flows. However, when the water in the boiler portion has lost a certain part of its heat, for example to a point slightly below the point 6'6, the boiler thermo-responsive member has decreased in resistance, producing a smaller unbalance of the bridge 25 and a voltage more positive than the critical value is impressed on the grid 56'. Plate current now flows; the relay is energized; the contacts 150 and 15b are closed; and the circuit comprising the motor 2i and the source of alternating current applied between the leads and 8| is completed. The

motor then is operative and fuel from the hopper 20 is fed into the fire-box l of the furnace. The added fuel produces a hotter fire and the temperature in the boiler It becomes higher.

' When the water in the boiler It has risen to a point slightly above the point 81, the resistance of the boiler member 22 is increased, and the bridge 25 is more greatly out of balance with a resultant more negative voltage bias on the grid 56; At this point the grid bias is more negative than the critical value for that grid at the particular outside temperature, the discharge and plate current through the tube will have ceased,

. similar to any ordinary gaseous discharge tube with plate and cathode connected to an alternating current source, and the contactors 75a. and l5b will have been opened by a spring (not shown) in the relay 75. The motor then will have stopped, and no more fuel will be fed into the fire-box l5. When the boiler water again cools to slightly below point 81', the cycle of operations is repeated. Thus the bridge 25 and the boiler thermo-responsive member 22 function to maintain the boiler temperature onan average at a tive. Assuming the tube operative, the water in the boiler I6 must now become hotter to a point slightly above the point 89, corresponding to the point 88, thus producing a greater unbalance of the bridge 25 before the voltage on the grid 56 is sufiiciently negative to cause the discharge through the tube to'cease, By the action of the bridge 25 and the boiler member 22 the boiler temperature is kept on an average at the higher value 89; the resultant average steam pressure is higher; and more heat is being delivered to the either up or down and selects the range of water temperatures at which the heating system shall operate. Adjusting the resistor 42 has the eflect of rotating the curve either clockwise or counterclockwise about the point 90 or in other words itchanges the number of degrees rise of the water in the boiler corresponding to 1 drop of the outside temperature. Functionally the resistor 62 acts to change the voltage input to and the voltage output of the bridge 32 and also the rate at which the critical voltage value of the grid 56 changes with the outside temperature.

My improved heat production control arrangement does not rely on a change of inside temperature to cause a change in the rate heat is supplied, but rather maintains a substantially constant inside temperature by causing the rate heat is supplied to vary properly with the outside temperature.

economically since the excess heat losses of the interior of the building. When the outsidetemperature rises again to the point 86, for example, the resistance of the outside member 23 is higher, there is a greater unbalance of the bridge 32, and

the grid 69 becomes more negative. This causes the critical voltage of grid 56. to again become more positive with aresultant decreasein the average boiler'temperature to the corresponding point 81. The average boiler pressure and the quantity of the heat delivered to the interior of the building are correspondingly decreased. In effect then, the outside temperature responsive member 23 and the bridge 32 function to set the I rate or pace of heat production, or in other words .of adjustable resistors 21 and 34, respectively.

Referring to the graph of Fig. 2, adjusting the resistor 34 has the effect of moving the point 90,

as well as the curve as a whole either to the left I or to the right, the point 90 being the intersection of the curve with the horizontal axis -of the graph. Adjusting the resistor 21 has the effect of moving the point 90 as well as the whole curve The heating system operates adjusting means may be readily calibrated, and.

.the latitude of adjustment in a single embodiment of my arrangement is such that it can be used with a variety of different types of heating systems.

While I prefer to employ the form of arrangement as shown in my drawing and as above described,it is to be understood that my invention is not to be so limited except only in so far as certain of the appended claims may be so limited, as it will be understood that changes in the form of arrangement may be made without departing from the spirit of my invention.

I claim: I r

1. In a system for controlling the heat supplied to a heated structure from a source pro.- vided with temperature control means including an electric switch, the combination of an electron tube provided with an output circuit including means for controlling said switch and with a pair of input circuits, means including one bridge circuit for applying to one of said input circuits a potential which is responsive .to the temperature of said heat source, means including another bridge circuit for applying tothe other of said input circuits a potential which is responsive to a temperature outside said structure, and means for adjusting the relation between the responses of said input circuits to said heat source and outside temperatures.

2. In a system for controlling the heat supplied to a heated structure from a source provided with temperature control means including an electric switch, the combination of an electron tube provided with an output circuit including means for controlling said switch and with a pair of input circuits, means including one bridge circuit for applying to one of said input circuits a potential which is responsive to the temperature 7 of said heat source, means including another bridge circuit for applying to the other of said input circuits a potential which is responsive to a temperature outside said structure, and means including a resistor connected in shunt to one of said input circuits foradjusting the relation between the responses of said input circuits to said heat source and outside temperatures.

3. In a system for controlling the heat supplied to a heated structure from a source provided with temperature control means including an electric switch, the combination of an electron tube provided with an output circuit including means for controlling said switch and with a pair of input circuits, means including one bridge circuit for applying to one of said input circuits a potential which is responsive to the temperature of said heat source, means including another bridge circuit for applying to the other of said input circuits a potential which is responsive to a temperature outside said structure, a potential source connected to energize said bridge circuits, and means including a resistor connected between said potential source and one of said bridge circuits for adjusting the relation between the responses of said input circuits to said heat source and outside temperatures.

4. In a system for controlling the heat supplied to a heated structure from a source provided with temperature control means including an electric switch, the combination of an electron tube provided with an output circuit including means for controlling said switch and with a pair of input circuits, means including one bridge circuit for applying to one of said input circuits a potential which is responsive to the temperature of said heat source, means including another bridge circuit for applying to the other of said input circuits a potential which is responsive to a temperature outside said structure, and means for adjusting the rate at which the voltage of one of said input circuits changes in response to change in temperature.

5. In a system for controlling the heat supplied to a heated structure from a source provided with temperature control means including an electric switch, the combination of an electron tube provided with an output circuit including means for controlling said switch and with a pair of input circuits, means including one bridge circuit for applying to one of said input circuits a potential which is responsive to the temperature of said heat source, means including another bridge circuit for applying to the other of said input circuits a potential which is responsive to a temperature outside said structure, and means for adjusting the rate at which the voltage of said outside temperature responsive input circuit changes in response to change in outside temperature.

6. In asystem for controlling the heat supplied to a heated structure from a source provided with temperature control means including an electric switch, the combination of an electron tube provided with an output circuit including means for controlling said switch and with a pair of input circuits, means including one bridge circuit for applying to one of said input circuits a potential which is responsive to the temperature of said heat source, means including another bridge circuit for applying to the other of said input circuits a potential which is responsive to a temperature outside said structure, and means including a capacitor connected in shunt to one of said input circuits for protecting said electron tube against surges in the voltage applied thereto.

7. In a system for controlling the heat supplied to a heated structure from a source provided with temperature control means including an electric switch, the combination of an electron tube provided with an output circuit including means for controlling said switch and with a pair of input circuits, means including one bridge circuit for applying to one of said input circuits a potential which is responsive to the temperature of said heat source, means including another bridge circuit for applying to the other of said input circuits a potential which is responsive to a temperature outside said structure, and means for adjusting the magnitude of the unbalance of said bridges.

FREDERICK J. WEY HER. 

